对桥梁抗风规范斜拉桥基频近似公式的改进

Improvement of Approximate Formula in Wind-Resisitent Design Specification for Highway Bridges

其于理论推导与国内外大跨度斜拉桥实桥分析统计资料,拟合出了形式更加简单、而且具有较高精度的斜拉桥基频(一阶竖弯和扭转)估算公式。与现行规范公式比较,推荐一阶竖弯频率估算公式不仅估算精度高,而且在表达形式上与扭频估算公式相统一,更能体现出结构竖弯频率与扭转基频这二者之间的内在联系,是对桥梁抗风规范基频近似公式的一次极好的改进。与国内外诸多大桥有限元动力分析对比结果表明,推荐公式对400m以上跨径的双塔斜拉桥动力分析具有较强的实用性和准确性,能更好地指导工程实践。

A new approximate formula of fundamental frequency-（base frequency of bengding and tori- sion） for the longspan cable-stayed bridge is developed based on the theoretical derivation and many global bridge analysis cases. This formula not only improves the accuracy, but also has simple expression. The recommend formula is a critical improvement for the fundamental frequency from Wind-resisitent Design Specification for Highway Bridges （JTG/T D60-01-2004）. It has unified expression form with the vertical bending formula, and reveals the true relationship between the structure bending frequency and torsion frequency. Comparison between the finite element dynamic analysis results and the calculated results, shows that our formula is reliable and has high precision for the real engineering practice on the twin-tower cable-stayed bridge with a span over 400 m.